The overall objective of this research project is to develop methods and techniques which will improve the safety of open heart surgery by reducing damage to the heart during the course of surgery. Although the heart-lung machine (cardiopulmonary bypass) supports all of the other organs of the body while we operate directly on the heart, by necessity we interrupt nutrient blood flow while operating on or inside of the heart. We have been investigating such protective measures as reducing the heart temperature and inducing complete cardiac arrest in order to lower the heart's metabolic needs while it is deprived of blood. More recently we have examined the effects of various drugs and chemicals administered to the heart at the onset of this bloodless period. Other investigations have been directed at developing new methods of measuring blood flow to the heart using a mass spectrometer. Finally, we have continued our previous studies of pulsatile cardiopulmonary bypass perfusion, using a simple device which converts linear, roller pump perfusion to pulsatile flow. These studies will be continued.